i locked the blms to 128 and tuned using the int which has worked well. i only have one fuel table and when i stood on the peddle the truck began to miss and backfire, why! i increased the pe/tps (pumpshot) to 20% less of what the 454 values are on a different bin, still doing the same. below was the data when the motor began backfiring and missing:

map 91.5kpa
rpm 3100
blm 128
int 127
tps% 74.1
tranny gear d3
spark advance 15.1
egr promed out
knock retard promed out

383 stroker, 64cc 23deg trickflow heads c/w edlebrock performer intake and adapter, cam is an extreme 4x4 comp. Cam. 12-235-2 grind ( .447/.462 lift, duration 210 218 lift @50, 111 lobe separation) . unit has hypr. Flattop floating pistons, eagle cast crank, 5.7eagle rods. 10.2:1 comp. Headers c/w 2.5” flowmaster exhaust. 16147060 pcm, $85def


I

 

Why only 74% Throttle, and 15d timing?.
Do you have a commanded AFR value?

 

i just finished building and i have not wanted to take the engine over the 3000rpm point until i had about 100miles. today i punched it alittle and this is the hardest i stood on peddle and the backfire/stumble just is one point it happened at. the target afr is 14.7 and i forgot to mention the i have a 454tbi 80lb injectors set to 120bpw. i have been tuning the fuel table for several days now at the under 3000 rpm and thing look good, blms are staying at 128. i was a little shocked having to see this backfire and miss. the spark table is close to a stock 747 ecm asdu.bin. this thing feels like a fueling problem, this spark curve worked on my stock 350 and this is why i think it is a fuel thing. how does the pump shot work? could it be not enough at the higher rpms. my fuel table only goes to 4800rpm.

the truck real moves nicely when you just drive normally and i have had it to 3500rpm with no stumble or backfire. it just happens when you stand on the throttle hard and hold it, but i am by no means pushing it to the floor.

 

[QUOTE]Originally posted by Grumpy:
[B] Why only 74% Throttle, and 15d timing?.
Do you have a commanded AFR value?

grumpy, i do have this table:

wot air fuel ration vs rpm

rpm air ration
800 12.2
1200 12.3
1600 12.3
2000 12.4
2400 12.2
2800 12.0
3200 11.8
3600 11.4
4000 11.4

what exactly does this do?

also, with the blm locked to 128 will this cause some problems when you punch the throttle?





[This message has been edited by prscarf (edited June 02, 2001).]